Many scientists contend that release of halogen refrigerants into the atmosphere deleteriously affects the ozone layer that surrounds and protects the earth from ultraviolet solar radiation. Recent international discussions and treaties, coupled with related regulations and legislation , have renewed interest in devices for recovery and storage of used refrigerants from refrigeration equipment for later purification and reuse or for proper disposal. U.S. Pat. No. 4,261,178, assigned to the assignee hereof, discloses a refrigerant recovery system in which the inlet of a compressor is coupled through an evaporator and through a manual valve to the refrigeration equipment from which refrigerant is to be recovered. The compressor outlet is connected through a condenser to a refrigerant storage container. The condenser and evaporator are combined in a single assembly through which cooling air is circulated by a fan. Content of the storage container is monitored by a scale on which the container is mounted for sensing weight of liquid refrigerant in the container, and by a pressure switch coupled to the fluid conduit between the condenser and the container for sensing vapor pressure within the storage container. A full-container condition sensed at the scale or a high-pressure condition sensed at the pressure switch terminates operation of the compressor motor. A vacuum switch is positioned between the inlet valve and the evaporator for sensing evacuation of refrigerant from the refrigeration system and automatically terminating operation of the compressor motor.
U.S. Pat. Nos. 4,768,347 and 4,809,520, also signed to the assignee hereof, discloses a refrigerant recovery system that includes a compressor having an inlet coupled through an evaporator and through a solenoid valve to the refrigeration equipment from which refrigerant is to be withdrawn, and an outlet coupled through a condenser to a refrigerant storage container or tank. The refrigerant storage container is carried by a scale having a limit switch coupled to control electronics to prevent or terminate further refrigerant recovery when the container is full. The scale comprises a platform pivotally mounted by a hinge pin to a wheeled cart, which also carries the evaporator/condenser unit, compressor, control electronics, and associated valves and hoses.
Although the systems disclosed in the noted patents address and overcome problems theretofore extant in the art, further improvements remain desirable. For example, a problem remains relative to controlling inlet flow to the evaporator and compressor so as to maximize overall recovery speed and efficiency for either liquid, vapor or mixed liquid/vapor phase inlet refrigerant, while ensuring that refrigerant at the compressor is in vapor phase so as to prevent slugging at the compressor. It is also desirable to control the inlet refrigerant flow in such a manner as to minimize superheating of the refrigerant in the evaporator, which reduces efficiency of the handling system and the amount of refrigerant that can be pumped therethrough.
It is therefore a general object of the present invention to provide a refrigerant handling system, such as a refrigerant recovery system, that includes the capability of handling inlet refrigerant in either vapor phase, liquid phase or mixed liquid/vapor phase, that is adapted to optimize flow of refrigerant therethrough a function of inlet refrigerant phase, and that ensures that refrigerant at the compressor inlet is in vapor phase so as to prevent slugging and possible damage to the compressor. Another and related object of the present invention is to provide a refrigerant handling system of the described character that operates automatically without operator invention. A further object of the present invention is to provide a refrigerant handling system of the described character in which flow of refrigerant to the evaporator is optimized for enhanced heat exchange with the refrigerant condenser while substantially reducing or preventing superheating of the refrigerant.